664 LETTERS TO THE EDITOR Ahmet Yükseka, Yüksel Elab, Elif Do˘gan Bakib,∗,
Serdar Kokulub
aAfyon Kocatepe University, Faculty of Medicine,
Anesthesiology and Reanimation Department, Afyonkarahisar, Turkey
bKocatepe University, Faculty of Medicine, Anesthesiology
and Reanimation Department, Afyonkarahisar, Turkey
∗Corresponding author.
E-mail:elifbaki1973@mynet.com(E.D. Baki). http://dx.doi.org/10.1016/j.bjane.2016.02.004
0104-0014/
© 2016 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/).
Severe
hypoxemia
follows
hypoxic
pulmonary
vasoconstriction
and/or
hypoxic
pulmonary
vasoconstriction
inhibition
by
inhaled
anesthetics:
prognostic
potential
of
100
% shunt
fractions
Hipoxemia
grave
após
vasoconstric
¸ão
hipóxica
pulmonar
e/ou
inibic
¸ão
da
vasoconstric
¸ão
hipóxica
pulmonar
por
anestésicos
inalatórios:
potencial
prognóstico
de
frac
¸ões
de
shunt
de
100%
DearEditor,
HypoxicPulmonaryVasoconstriction(HPV)wasfirstreported byBindsleyetal.inadultpatientsandwasmanagedusing double lumen catheters to ventilate one lung with 100% oxygen and the other with 95% N2 and 5% oxygen during intravenousbarbiturateandfentanylanesthesia.1However, ‘‘HPV inhibition’’ has predominantly been attributed to theuse of inhalation agents andis considered as acause of hypoxia duringanesthesia. Moreover,both in vitro and in vivo studies have demonstrated that inhalation agents inhibit HPV under a range of conditions,2---5and sevoflu-ranehasbeenshowntodecreaseHPVinadose-dependent manner.4,6,7
Case
description
Herewereportacaseofseverehypoxemiaduring sevoflu-raneinduction ina 6year-oldboy whowasscheduled for adenotonsillectomy.The patientwastreated according to AmericanSocietyofAnesthesiology(ASA)classIandweighed 22kg. Pre-operative assessments, physical examinations, andlaboratoryinvestigationswere unremarkable,andthe patienthadahemoglobinlevelof12mg.dL−1anda hemat-ocritof36%.Followingtransfertotheoperatingroomwith nopre-medication,routineElectrocardiography(ECG), non-invasiveblood pressure, andSpO2 levels weremonitored. Anesthesiawasintroduced viaa facemaskand apediatric circlesystemproviding8%sevofluranein100%oxygenata flow rate of 6L.min−1. Subsequently, sevoflurane concen-trationswerereducedto5%withinthefirstminuteandto
2% on loss of eyelash reflexes. Following intravenous can-nulation, rocuronium (0.6 mg.kg−1) was administered, and SpO2 levels rapidly and progressively decreased from 98% to 38% at 10 and 15 min of induction, respectively, with no clinical explanation. As a consequence, the patients’ Heart Rate (HR) suddenly decreased from 109 to 90 bpm in response to hypoxia, and sevoflurane concentrations were reduced to 2% and subsequently discontinued prior to tra-cheal intubation and ventilation with 100% oxygen. Efficient lung ventilation was possible throughout the period. A clini-cal improvement was observed within seconds of intubation and ventilation, and SpO2 levels and HR returned to 100% and 118 bpm, respectively. No blood pressure abnormali-ties were observed during the procedure, and the rapid restoration of SpO2and HR with 100% oxygen was considered symptomatic of an adverse drug reaction. Thus, anesthe-sia was maintained with 1%---1.5% sevoflurane and oxygen in 50% N2O.
Discussion
HPV is considered as a protective mechanism that opti-mizes systemic oxygen delivery. Thus, the inhibition of HPV by inhalational agents is believed to cause hypoxia during anesthesia. However, the protective effects of HPV against hypoxia may depend on the size of affected lung regions. Lung tissues are globally affected by all pulmonary anesthet-ics, and sevoflurane has been shown to induce pulmonary vessel dilatation in normoxia.7 Therefore, HPV should be considered as a multifactorial response to local or global pulmonary hypoxia during acute hypoxia. Thus, the present observations suggest that the degree of acute local shunting can be used to determine whether HPV mechanism is use-ful or not. The type of anesthetics can be significant with regard to this reaction.
LETTERSTOTHEEDITOR 665 hypoxemiaundercertainconditions.However,the
relation-shipbetweenpulmonaryanestheticadministrationandHPV remainscontroversial.
Inconclusion,globaleffectsofinhalationinductionwith sevofluraneathighconcentrationsmaycauseoxygen desat-uration in lungs that are normally ventilated with 100% oxygen, potentially resulting in global inhibition of HPV. However,theseconditionsmaybeaconsequenceofglobal HPV and associated 100% shunt fractions. Thus, despite thehighlevel evidenceofnodifferencesin outcomes fol-lowingpulmonaryandintravenousanesthesia, thehypoxic consequencesofinhalationanesthesiarequirefurther clar-ification.
Consent
Writteninformedconsentwasobtainedfromthepatientfor publicationofthiscasereport.Acopyofthewrittenconsent isavailableforreviewbytheEditorofthisjournal.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
References
1.Bindslev L, Jolin A, Hedenstierna G, et al. Hypoxic pul-monaryvasoconstrictioninthehumanlung:effectofrepeated hypoxicchallengesduringanesthesia.Anesthesiology.1985;62: 621---5.
2.MarshallC,LindgrenL,MarshallBE.Effectsofhalothane, enflu-rane,andisofluraneonhypoxicpulmonaryvasoconstrictioninrat lungsinvitro.Anesthesiology.1984;60:304---8.
3.Domino KB, Borowec L, Alexander CM, et al. Influence of isofluraneonhypoxicpulmonaryvasoconstrictionindogs. Anes-thesiology.1986;64:423---9.
4.IshibeY,GuiX,UnoH,et al.Effectofsevoflurane onhypoxic pulmonary vasoconstrictioninthe perfusedrabbitlung. Anes-thesiology.1993;79:1348---53.
5.LoerSA,ScheerenTW,TarnowJ.Desfluraneinhibitshypoxic pul-monaryvasoconstrictioninisolatedrabbitlungs.Anesthesiology. 1995;83:552---6.
6.KerbaulF,BellezzaM,GuidonC,etal.Effectsofsevofluraneon hypoxicpulmonaryvasoconstrictioninanaesthetizedpiglets.Br JAnaesth.2000;85:440---5.
7.Liu R, Ueda M,Okazaki N, et al. Roleof potassiumchannels in isoflurane- and sevoflurane-induced attenuation ofhypoxic pulmonary vasoconstriction in isolated perfused rabbit lungs. Anesthesiology.2001;95:939---46.
MenekseOksar∗,OnurKoyuncu,SelimTurhanoglu
MustafaKemalUniversityFacultyofMedicine,Department ofAnesthesiologyandReanimation,Hatay,Turkey
∗Correspondingauthor.
E-mail:menekseoksar@gmail.com(M.Oksar). http://dx.doi.org/10.1016/j.bjane.2016.02.003
0104-0014/
©2016SociedadeBrasileiradeAnestesiologia.Publishedby ElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense( http://creativecommons.org/licenses/by-nc-nd/4.0/).
Anesthesia
in
a
newborn
with
Klippel---Feil
syndrome
Anestesia
em
recém-nascido
com
síndrome
de
Klippel-Feil
DearEditor,
IreadthecasereportofAltayetal.1aboutanesthesia man-agementofanewbornwithKlippel---Feilsyndrome(KFS)with interest.Theauthorspresentedtheircaseas‘‘theyoungest child withKFS onwhomoral intubation wasperformed’’. I appreciate the colleagues for their management of this challengingcase,buttherearesomepointsthathavetobe discussed.
Altay et al. performed a successful intubation at first attemptwithDirectLaryngoscopy (DL),which was consis-tent with the literature. According tothe literature, KFS alonemaynotbeapredictorofdifficultairwaymanagement in infants. Naguib et al.2 had reported a three-week-old boy diagnosed with KFS successfully intubated with DL.
DOIofreferstoarticle:
http://dx.doi.org/10.1016/j.bjane.2014.03.006
Creightonetal.3hadreported8infantswithKFS(6ofthem had alsocleft palate, most probablysome of them were newborns)onwhomoralornasalintubationwasperformed withDLusingregularlaryngoscope.Theyperformedawake DLsuccessfully, despite theother present conditionsthat complicateintubationlikecleftpalateandlateralposition inadditiontoKFS.
Recentlywehavereviewedtheairwaymanagementand the success of DL in children with KFS4 and found that thereis no report describing difficult mask ventilation or unsuccessfulLaryngeal MaskAirway(LMA)insertion inthe literature. Also,there is no report of an unsuccessful DL ininfantswithKFS.Wethinkthatthesuccessrateof tra-cheal intubation with DL in early ages (probably before adolescence)seemstobeincreasedwhenotherpredictors ofdifficult intubationdoes not accompany.Thesefindings mayencourage usfor attemptingDL in children withKFS alone,butaccompanying airwayanomalies arenotrarein KFSandhavetobeinvestigatedbeforeanesthesiainduction. Also,a previous successfulDL does not ensure successful intubation because cervical fusion may become progres-sivelyworsenovertimeandDLmaybechallenginginolder ages.
